Field of the Invention
The invention relates to providing motor drive for an element that is movable relative to a stationary structure. The invention relates in particular to actuators for providing motor drive for a movable flight control surface of an aircraft, such as a rudder, an aileron, an elevon, a flap, . . . .
Brief Description of the Related Art
An aircraft has flight control surfaces, such as flaps, that are movable between a deployed position and a retracted position, and that are moved between their two positions by actuators. Initially such actuators were purely mechanical, before being replaced by hydraulic actuators. In more recent aircraft, hydraulic actuators are now being replaced more and more by electrical actuators.
Such an electrical actuator comprises a housing containing an electric motor that is provided with means for connecting it to an electrical power supply of the aircraft and that possesses an outlet shaft that engages with the flight control surface via a movement transmission device such as a screw-and-nut device.
For certain maintenance operations while the aircraft is on the ground, it must be possible to move the flight control surfaces. It is then necessary to power the actuator and to control it in order to perform the desired movement. That complicates maintenance procedures, in particular for reasons of ensuring personnel safety.